Hydrodynamics of sponge pumps and evolution of the sponge body plan.

Gitai Yahel,Sally P Leys,Jens H Walther,Seyed Saeed Asadzadeh,Poul Scheel Larsen,Thomas Kiørboe

doi:10.7554/elife.61012

Gitai Yahel, Sally P Leys + Show 4 more

Open Access

https://doi.org/10.7554/elife.61012

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Abstract

Sponges are suspension feeders that filter vast amounts of water. Pumping is carried out by flagellated chambers that are connected to an inhalant and exhalant canal system. In 'leucon' sponges with relatively high-pressure resistance due to a complex and narrow canal system, pumping and filtering are only possible owing to the presence of a gasket-like structure (forming a canopy above the collar filters). Here, we combine numerical and experimental work and demonstrate how sponges that lack such sealing elements are able to efficiently pump and force the flagella-driven flow through their collar filter, thanks to the formation of a 'hydrodynamic gasket' above the collar. Our findings link the architecture of flagellated chambers to that of the canal system, and lend support to the current view that the sponge aquiferous system evolved from an open-type filtration system, and that the first metazoans were filter feeders.

Highlights

Many aquatic suspension feeders use cilia and flagella to generate feeding flows from which they capture prey particles
A narrow and long ostium with higher resistance to flow results in a reduced pumping rate but an increased retention efficiency as the hydrodynamic gasket is located below the tip of the collars and the stronger backflow is more efficient in preventing flow from bypassing the collar filter (Appendix 1-Fig. 4)
The results show that beat synchronization among choanocytes is not necessary for the functionality of the pump

Summary

Introduction

Many aquatic suspension feeders use cilia and flagella to generate feeding flows from which they capture prey particles. The flow passing through the collar (filtration rate) is several times higher than the flow through the ostium (pumping rate) ( Fig. 3C), suggesting that a large proportion of the water is re-filtered inside the chamber.

Results

Conclusion